Hi:
I have a 1999 Tacoma Pre-Runner 3.4L. While driving home My Taco.. started to shake, like if a spark plug failed. When the engine is cold it runs like a breeze but when hot it starts to shake. The computer read P306. The mech.. changed the 6th cyl. coil but it's still shaking. He checked the sparks and cables but everything was Ok. I cleaned the injector connector with electronic contact cleaner but did not work. Please help.

The Sparks were OK, I did not change the cables, that will be my first move. I'll change the cables then if that doesn't work I'll go for the injector. By the way, can you tell me what did you mean by the injector "stuck open"? I'm not a mechanic that's why I'm asking.
Thanks

The injectors deliver intermittent shots of fuel to your cylinders for combustion, if they get stuck open, it just means your constantly doseing that cylinder with fuel, making it too rich to ignite properly

The Sparks were OK, I did not change the cables, that will be my first move. I'll change the cables then if that doesn't work I'll go for the injector. By the way, can you tell me what did you mean by the injector "stuck open"? I'm not a mechanic that's why I'm asking.
Thanks

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If the cable does not fix it, I would suggest getting a compression test done. It should be 125 psi or higher

Well, k5blaser88, I replaced the wires but did not work. It was the 6th cylinder injector! I changed it and hey! the failure is gone. I spent quite an amount of $ but I'm glad I did. The fact is that the injectors are not so accesibles (at least in my 1999 Tacoma Prerunner 3.4L) the mech. had to retired the "Plenum", that's a big piece of metal located at the top of the engine. You can start changing the wires because you should change them anyway and then if that does not solves your problem then go for the injector. I hope this helps.